1. Field Of The Invention
The present invention relates generally to magnetic recording apparatus. More specifically, the present invention relates to a multitrack magnetic head assembly for in-contact linear recording.
2. Description Of The Prior Art
In the following description of relevant prior art, reference is made to FIG. 1 of the accompanying drawings, which is a perspective view of a multitrack magnetic head assembly 10 known in the art.
Before addressing structural features and specific limitations of the head assembly 10, reference is made to the fact that the transducing gap of a magnetic head, where possible, should be placed in contact with its associated recording medium to enhance the strength of the signal recorded on or played back therefrom. This is particularly important in an application involving the recording of short-wavelength signals wherein it otherwise would be imperative that intimate contact be maintained at a media-to-head interface to minimize spacing losses.
Referring now to FIG. 1, the head assembly 10 includes complementary half-sections 12a and 12b formed of a bulk magnetically soft material of good wear characteristics such as nickel iron ferrite. The half-sections 12a, 12b, which are commonly cemented together, cooperatively define an upwardly facing surface 13 which has a series of slots (not shown) at an interface 14 between the half-sections. At the end of these slots and between sections 12a and 12b are deposited flat conductive coils which together with the soft magnetic material of 12a and 12b form a series of hybrid thin film heads 16 in a side-by-side configuration with their respective transducing gaps substantially in alignment with the interface 14. A series of elongated parallel ribs 20 alternating with somewhat wider channels 21 is located on each side of the interface 14, extending orthogonal thereto. The ribs 20 function to support magnetic tape on the leading side and the trailing side of each head 16. For that purpose, each rib 20 is gently curved in the direction orthogonal to the interface 14. In the direction parallel with the interface 14, however, the tape-engaging surface of each rib 20 is substantially flat, forming a right angle with rib sidewalls 22, as shown in FIG. 1.
The channels 21, in each half of the head assembly 10, are aligned with the magnetic heads 16 and serve to form low-pressure regions at the head element such that a thin air bearing ensues at that part of the tape engaging surface.
In order to accommodate the magnetic heads 16 between opposing channels 21, the upwardly facing surface 13 includes an elongated relatively wide continuous land area 24 on both sides of the interface 14. The land area 24 has the same curvature as the ribs 20 in the direction orthogonal to the interface 14.
Although the head assembly 10 performs acceptably for relatively long wavelength applications, recording/playback performance has performed less well for relatively short wavelength applications. We have found that the reason for this is the head assembly 10 does not provide satisfactory contact with magnetic tape. This, of course, results in spacing losses which for a given spacing are more severe for short-wavelength signals than for longer wavelengths.
We believe these spacing losses arise from at least two factors. First, the contour of the upwardly facing surface 13 itself causes tape to at least not be in continuous contact with all transducing gaps of all magnetic heads 16 all the time. Second, we have found that the channels 21 between adjacent ribs 20 tend to collect contamination from tape oxide formulations. This "debris" results in local interference with compliance of tape with the surface 13 of the head assembly.